To satisfy felt security goals in a specific relationship, people need to believe that their partner sees qualities in them that merit attention, nurturance, and care. However, people troubled by dispositional insecurities, such as low self-esteem or attachment-related anxiety, underestimate how positively their partner sees them on specific traits and even underestimate how much their partner loves them. This proposal examines how the resulting activation of felt security needs affects newlyweds' capacity to engage in the affective, cognitive, and behavioral regulation strategies critical for continued marital satisfaction. First, the proposal examines how feeling more or less positively regarded affects people's day-to-day threshold for perceiving signs of acceptance or rejection in specific events (appraisal sensitivity), how day-to-day concerns about rejection affect people's self-esteem (self-esteem sensitivity), and how feeling more or less positively regarded affects the behavioral strategies (i.e., interdependence and accommodation regulation) people adopt to alleviate the sting of rejection on a day-to-day basis. Second, the proposal examines how and why these within-person signatures or response profiles change over time, and how they relate to long-term changes in people's impressions of themselves and others, and to the long-term well-being of their marriage. A longitudinal daily diary study of newlywed couples is planned. Both members of the couple will complete 14-day electronic diaries and relationship-functioning assessments for 4 consecutive years. The daily diaries will be designed to provide within-person measures of how much rejection is read into events, within person measures of how much perceived rejections threaten self-esteem, and within-person measures of how each person responds behaviorally to feeling rejected. These micro-process indices will then be used to predict the relationship trajectories couples take, toward increasing, stable, or decreasing individual and relationship well-being. Apart from shedding light on the dynamics of attachment and interdependence regulation, this research might also facilitate the development of clinical interventions, such as fostering insight into a partner's positive regard and unconditional acceptance that might circumvent harmful interaction patterns.